JPH08508Y2 - Engine cylinder head structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to a cylinder head structure of an engine in which a cam shaft is arranged in a cylinder head.

(Prior Art) Some engines have a camshaft arranged in a cylinder head, and this type of engine is called an OHC type.

By the way, a head bolt is arranged in a cylinder head of an OHC type engine so as to correspond to a cam journal portion that rotatably supports a cam shaft. That is, the cylinder head is fastened to the cylinder block by a head bolt, and the boss portion of the head bolt is
It is provided on the side of the cam journal portion, at the intermediate portion in the extending direction of the cam shaft, that is, at the journal center.

However, the head bolt corresponding to the end cam journal portion that supports the end portion of the cam shaft is disclosed in JP-A-62-139.
As seen in Japanese Patent No. 953, it is customary to arrange the end cam journal portion offset from the journal center. That is, as also shown in FIG. 4, of the cam journal portion 2 projectingly provided on the floor surface of the cylinder head 1 and the head bolt boss portion 3 provided on the side of the cam journal portion 2 at the end portion of the cylinder head 1. The position of the end cam journal portion 2a and the corresponding head bolt boss portion 3a are such that the head bolt boss portion 3a extends from the journal center 1 of the end cam journal portion 2a to the cylinder head 1
It is generally arranged to be largely deviated to the side wall 1a of the end portion.

For this reason, the end cam journal portion 2a is inclined due to the axial force of the head bolt as shown in FIG. 5, so that the cam shaft is apt to seize. In the figure, the arrows indicate the position of the head bolt and the direction of its axial force.

Therefore, an object of the present invention is to provide a cylinder head structure for an engine in which the inclination of the end cam journal portion due to the axial force of the head bolt is suppressed.

(Means and Actions for Achieving Technical Problem) In order to achieve the above technical problem, in the present invention, a head bolt for fastening a cylinder block and a cylinder head, and a head bolt provided on the cylinder head. A cam shaft; and an end cam journal portion protruding from the floor surface of the cylinder head and supporting an end portion of the cam shaft, the boss portion of the head bolt located in the vicinity of the end cam journal portion. Assuming that the engine is arranged offset from the journal center of the end cam journal portion, the cylinder head has a connecting portion that connects the end cam journal portion and an end side wall of the cylinder head. Is provided, and the connecting portion is arranged apart from the floor surface of the cylinder head.

With such a configuration, the inclination of the end cam journal portion can be suppressed by the support of the connecting portion. Further, since the connecting portion is provided away from the floor surface of the cylinder head, the existence of the connecting portion does not hinder the flow of oil flowing along the floor surface of the cylinder head.

Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings.

1 to 3, reference numeral 10 is a cylinder head for an OHC type engine.
At the end of the cam shaft (not shown) in the extending direction, an end cam journal portion 11 protruding from the floor surface 10a of the cylinder head 10 and a head bolt boss portion 12 arranged in the vicinity thereof are formed. Has been done.

The end cam journal portion 11 is of a plug-in type, and the end cam journal portion 11 is formed with a hollow bearing portion 11a into which a cam shaft is inserted, and a thrust groove 11b is formed above the hollow bearing portion 11a. Then, a regulation member (not shown) is fitted into the thrust groove 11b, and the displacement of the cam shaft in the axial direction is regulated by the regulation member. In the figure, 13 is a rocker shaft (not shown)
For journals.

The boss portion 12 is arranged laterally of the end cam journal portion 11 and offset from the middle portion in the extending direction of the cam shaft.

That is, since the thrust groove 11b is formed in the end cam journal portion 11 as described above, the journal rigidity of that portion is reduced. Therefore, the boss portion 12 is deviated from the journal center 1 toward the end side wall 10b of the cylinder head 10 so that the deformation of the thrust groove 11b due to the tightening of the head bolt is suppressed as much as possible.

An oil return hole 14 and a blow-by gas passage 15 are opened in the floor surface 10a of the cylinder head 10 between the boss portion 12 and the end side wall 10b of the cylinder head 10.

In addition, the end cam journal portion 11 and the end side wall 10b of the cylinder head 10 are connected to each other by a connecting portion 16 connecting the both 11 and 10b. This connection 16
Is exactly shaped to cover the upper half of the camshaft,
The upper surface 16a of the connecting portion 16 is a semicircular arc surface, and the connecting portion 1
A cavity 17 is formed between 6 and the floor surface 10a of the cylinder head 10. That is, the cavity 17 connects the space 18 on the oil return hole 14 side and the space 19 on the blow-by gas passage 15 side located on both sides of the connecting portion 16 with the connecting portion 16 interposed therebetween.

With the above configuration, the inclination of the end cam journal portion 11 due to the head bolt boss portion 12 being offset from the journal center 1 is prevented by the support of the connecting portion 16. Further, since the upper surface 16a of the connecting portion 16 is an arcuate surface, as shown by an arrow 20 in FIG. 2, the oil flows down uniformly left and right, and further, the spaces 18 and 19 are formed. Since the spaces are communicated by the cavity 17, the oil return property to the oil return hole 14 or the blow-by gas passage 15 is not hindered.

(Effects of the Invention) As is apparent from the above description, according to the present invention, the head cam bolt is disposed offset from the journal center of the end cam journal portion, so that the end cam journal portion Inclination can be prevented without impairing the oil return property.

[Brief description of drawings]

1 is a partial plan view showing an end portion of a cylinder head to which the present invention is applied, FIG. 2 is a sectional view taken along line II-II shown in FIG. 1, and FIG. 3 is shown in FIG. A sectional view taken along the line III-III, FIG. 4 is a partial plan view of a cylinder head showing an example of a conventional technique, and FIG. 5 is an explanatory view showing a problem of the conventional technique. 10: Cylinder head 10a: Cylinder head floor 10b: Cylinder head end side wall 11: Other cam journal 12: Head bolt boss 16: Connection 17: Cylinder head floor and connection Cavity l: Journal Center

Claims (1)

[Scope of utility model registration request] 1. A head bolt for fastening a cylinder block and a cylinder head, a cam shaft disposed on the cylinder head, and an end projecting from a floor surface of the cylinder head and supporting an end portion of the cam shaft. An end cam journal portion, the boss portion of the head bolt located near the end cam journal portion being arranged offset with respect to the journal center of the end cam journal portion. The head is provided with a connecting portion that connects the end cam journal portion and an end side wall of the cylinder head, and the connecting portion is arranged apart from a floor surface of the cylinder head. Engine cylinder head structure.